This was my thought, too.
Why does the phone company get to say "phone X cannot connect to my network; phone Y is welcome"? Surely if both phones are approved by the regulatory body, they should both be permitted to connect.
I moved away from the US back in 2012, and I seem to remember that while I was there I ran into some weird contracts with conditions like "you can only use a smartphone on our network if you sign up to a $60 a month data contract"...
I had no problem running my Nokia XM5800 on Cingular, though, with a cheapskate contract. But that was more like a smartphone than what passes for one these days.
- On-board maps and route-planning for the GPS (no network needed)
- On-board voice recognition (no network needed)
Nowadays, the phone is a camera, phone and display terminal for a load of processing done elsewhere ("in the cloud"), requiring either a WiFi or (more commonly) phone-network data connection.
The XM5800 was a great phone; it's such a pity that Nokia dropped the ball by not providing a proper app-store eco-system.